Jewelry products

ABSTRACT

THIS INVENTION PERTAINS TO THE MANUFACTURE OF JEWELRY AND TO ARTICLES OF JEWELRY HAVING THE APPEARANCE OF GOLD BUT IMPROVED SCRATCH RESISTANCE AND CONTAINING A MAJOR AMOUNT OF A METAL SELECTED FROM THE GROUP CONSISTING OF TANTALUM CARBIDE, ZIRCONIUM NITRIDE, TITANIUM NITRIDE AND VANADIUM NITRIDE AND A BINDER FROM THE GROUP CONSISTING OF IRON, COBALT, NICKEL AND THEIR ALLOYS.

United States Patent OffiCfi 3,684,463 Patented Aug. 15, 1972 3,684,463JEWELRY PRODUCTS Franz Koelbl, Salzburg-Parsch, Austria, assignor toSchwarzkopf Development Corporation, New York,

No Drawing. Filed Nov. 27, 1968, Ser. No. 779,635 Claims priority,application Austria, Dec. 1, 1967, 10,854/67 Int. Cl. B22f N US. Cl.29182.8 8 Claims ABSTRACT OF THE DISCLOSURE This invention pertains tothe manufacture of jewelry and to articles of jewelry having thephysical appearance of gold but improved scratch resistance andcontaining a major amount of a metal selected from the group consistingof tantalum carbide, zirconium nitride, titanium nitride and vanadiumnitride and a binder from the group consisting of iron, cobalt, nickeland their alloys.

This invention relates to the jewelry art and, more particularly, to themanufacture of articles of jewelry that are similar in appearance togold jewelry but at the same time are relatively resistant to scratchand crushing.

The articles of jewelry manufactured in accordance with this inventioncontain at least 70% by volume and up to 97% by volume of metalsselected from the group consisting of tantalum carbide, zirconiumnitride, titanium nitride and vanadium nitride. The jewelry articles cancontain one of the foregoing metals or it can utilize a mixture of twoor more of the aforesaid primary metals, as long as the totalconcentration of primary metal remains within the aforesaid range.

Preferably, the primary metal will be present in the articles of jewelryin an amount of from about 85 to 90% by volume.

The particular primary metal to be employed in any instance will dependto some extent upon the characteristics desired of the final product.Where it is desired that the article of jewelry approach very closelynot only the physical appearance but also the specific gravity of gold,then tantalum carbide is the preferred primary metal. Where a somewhatlesser specific gravity is desired, one of the other primary metals canbe employed.

The articles of jewelry should contain, in addition to primary metal, asuitable auxiliary metal. The auxiliary metal must be a metal having amelting point lower than the primary metal, preferably at least about 50C. less. The auxiliary metal must also be capable of wetting the primarymetal employed at the sintering temperature. Iron, cobalt and nickel andalloys of each of them, meeting the foregoing criteria, are satisfactoryauxiliary metals.

Nickel is the preferred auxiliary metal either by itself in the form ofthe commercial grade or pure nickel or in the form of alloys of nickeland chromium. Suitable nickelchromium alloys will contain from aboutfive to fifty percent by volume of chromium. In such nickel-chromiumalloys, copper can also be present in an amount from 1 to 30% by volume.When copper is present in the nickelchror nium alloy, the total volumeof chromium and nickel combined should not be greater than the volume ofnickel. A preferred auxiliary metal is an alloy containing 80 parts byvolume of nickel and 20 parts by volume of chromium. Nickel-molybdenumalloys are also suitable.

The quantity of auxiliary metal is preferably present in an amount of upto 20% by volume in the finished product. For some applications,particularly when used along with titanium nitride, up to 30% by volumeof auxiliary metals can be added. Most preferably, the auxiliary metalshould be present in an amount of at least 10% The combinations ofauxiliary and primary metals can be varied so as to achieve particularlydesirable properties. For example, a material can be achieved which willbe completely non-magnetic. Such a material would be useful for watchcases or the like. Using other combinations of primary and auxiliarymetals, the material achieved will be only weakly ferromagnetic, havinga saturation value of 41m lower than 20 gauss. In all instances, theproduct retains the characteristic color and outward physical appearanceof gold.

The gold colored articles made by means of this invention areparticularly useful when formed into items of jewelry such as, forexample, watch cases, watch bracelets and bands, rings, bracelets,charms and pins of all types. Utility is not, of course, limited tojewelry but can be used for other ornamental or utilitarian purposeswhere the cold coloration is necessary or desirable along with thestrength and scratch resistance produced by this invention.

The articles of this invention are prepared by conventional powdermetallurgical techniques from powdered starting materials. The primarymetal or metals along with any auxiliary metals are obtained and mixedin powdered form, pressed into the desired form, and thereaftersintered. Conventional lubricants can also be added to the mixture tofacilitate pressing.

The particle size of the powder is as in conventional powdermetallurgical processes. Sinten'ng will take place at the desiredsintering temperature for the composition used, the temperature beingwithin the range of 1200 to 2200 C. and for a time to achieve completesintering. Sintering preferably takes placein a protective atmosphere,i.e., an atmosphere that is non-reactive with the metallic componentspresent. Thus, for example, sintering can take place after evacuation ofair or it can take place in an atmosphere of an inert gas such as argon.

Alternatively, the powder mixture can be hot pressed into the desiredshape in a mold or other pressure device heated to the sinteringtemperature with a pressure of from about 50 to 350 kg. per cm. and atime of at least about 2 to 10 minutes.

Where it is desired to machine an item such as a watch case, the powdermixture can be compressed to bring the particles together into theproper shape, pre-sintered only very briefly and then finally sinteredat some later date. Because of the hardness of the product, machiningmay require the use of diamond tools.

After sintering, whether in an oven or through hot pressing, has beencompleted, the final article is then finished by grinding and polishingto bring out the lustre and smoothness desired.

The following example, which illustrates the preparation of a watch caseor part of it, represents the preferred mode of carrying out theinvention:

A mixture is prepared of parts by volume of commercial grade tantalumcarbide powder (which contains about 1% niobium carbide) and 15 parts ofcommercial nickel carbonyl powder. A suflicient amount of acetone isadded to facilitate blending and the mixture is ground in a conventionalball mill having cemented carbide balls. After the acetone evaporatesand a fine homogeneous powder is obtained, the powder is wetted with asolution of camphor in ether. After, the ether evaporates, with thecamphor remaining as a lubricant, the powder is poured into a mold andcompressed at a pressure of 1500 kg. per cm. The pressed compacts arethen pre-sintered for 15 minutes at 800 C. in a protective atmosphereformed by subjecting the sintering area to the action of a continuouslyacting vacuum pump. The pre-sintered compact is then machined withdiamond tools and sintered again at 1450 C. for one hour under the sameprotective atmosphere. The sintered parts, after cooling, are thenground to the -sistant than the comparable gold products.

required accurate dimensionsand polished. The resulting addition, areconsiderably harder and more scratch What is claimed is: 1. An articleof jewelry having. the color and physical appearance of gold and capableof being polished which consists essentially ofa sintered mixture ofbetween 70 and 90-parts lnyvolumeof at leastone compound of thegroupconsisting of tantalum carbide, zirconium nitride,

titanium nitride and vanadium nitride and between 10 and 30 parts byvolume of a metal of the group consisting of iron, cobalt, nickel andalloys thereof. 7 '2. An article according to claim 1 in which saidmetal is of the group consisting of nickel and nickel base alloys.

3. 'An article according to claim 1 in which said metal is anickel-chromium alloy containing about 5 to 50% by volume of chromium.

.4. An article according to claim]. containing zirconium nickel basealloys.

. 5. An article according to claim 1 containing titanium.

nitride and a metal of the group consisting of nickel and nickel basealloys.

'6. An article according to claim 1 containing vanadium nitrideandametal of the group consisting of nickel and nickel base alloys.

7. An article according to claim lcontainingtantalum carbide and a metalof the group consisting of nickel and I nickel base alloys. 7 I I 8. Anarticleaccording to claim 7 in which said metal is a nickel-chromiumalloy containing volume of chromium.

. References Cited UNITED STATES PATENTS 2,067,166 1/1937' Balke29-482.? 2,119,487 5/1938 Padowicz 29182.7 2,553,714 5/1951 Lucas29l82.7 2,979,811 4/1961 Toney 29-l 82.7 3,165,822 1/1965, Beeghly 29--182.7 g

3,369,892 2/1968 Ellis et al. 29- -1827 3,409,419 11/1968 Yates 29-1827nitride and a metal of the group consisting of nickel and CARLQUARFORTH"P1-1m-ary Exanuner B. H. HUNT, Assistant Examiner g Us.Cl.-X.R.

about 5 to-50% by Patent No. 3,684,463 Dated August 15, 1972 Inventmfls)Franz Koelbl It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

in In column 3 "90 parts" in line 10 should read 977 a "and between 10and" should be deleted in line 12; and "30 parts by volumeof" in line 13should read with the balance being Signed and Sealed this 3rd dayof'July 1973.

(SEAL) I Attest:

EDWARD M.FLETCH-ER,JR. e sz m yer Attesting Officer Acting Commissionerof Patents mg? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3,684,463 Dated August 1-5 1972 Inventofls) Franz Koelbl Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

T- In column 3 "90 parts" in line 10 should read 97% q "and between 10and" should be deleted in line 12; and

"30 parts by volume-of" in line 13 should read with the balance beingSigned and sealed this 3rdday of'July 1973.

Attest:

EDWARD M.FLETCH ER,JR. ene Tezt-myer Attesting Officer ActingCommissioner of Patents

